(1) Field of the Invention
The present relates to a multiphase converter controller, and more particularly relates to a multiphase converter controller with current balance.
(2) Description of the Prior Art
With the evolution of the process technology, the integrated circuit becomes gradually miniaturized while the driving voltage being reduced. However the power consumption of the integrated circuits in some field is not reduced with the reduction proportion of driving voltage. It results in that the operating current of the integrated circuit reversely increases.
A power supply for driving the integrated circuit is mainly supplied by a switching power supply. A switch operating of the switching power supply causes a voltage ripple in the supplied voltage. These voltage ripples is more obvious when the driving voltage of the integrated circuits lower, and even causes erroneous operation of the integrated circuit. For decreasing the voltage ripple of the switching power supply, a multiphase technology is developed. The multiphase technology transmits the power to the output end of the DC-DC converting circuit by the channels, so as to share the power with the multi-channel and reduce the amount of the voltage ripple.
Referring to FIG. 1, FIG. 1 is a schematic diagram of a conventional multiphase converter circuit. The multiphase converter circuit comprises a controller 10 and three channels 12a˜12c. Each of the channels 12a˜12c comprises two transistor switches connected in series between the input voltage Vin and the ground. Drivers of the channels 12a˜12c respectively receive pulse width modulating control signals PWM1˜PWM3 generated by the controller 10 and accordingly switch the corresponding transistor switches to provide channel currents Io1˜Io3.
The channel currents Io1˜Io3 commonly form an output current Io to charge a capacitance Co to generate an output voltage Vout for driving a load. The controller 10 detects the channel currents Io1˜Io3 through pin pairs CSP1 and CSN1, CSP2 and CSN2, and CSP3 and CSN3, and receives a voltage detecting signal FB and accordingly modulates the duty cycle of the transistor switches of the channels 12a˜12c. 
The channel currents are imbalance due to mismatch between components of the channels, such as transistor switches and inductances. The current imbalance decreases the life-span and reliability of the components. The controller 10 adjusts the amount of every channel current Io1˜Io3 to be balance according to the detecting signals of the pin pairs CSP1 and CSN1, CSP2 and CSN2 and CSP3 and CSN3. In general, the controller 10 first gets a reference duty cycle of every channel acquires by error amplifiers executing a feedback control, and then pulse width control circuits of the channels respectively compensates the reference duty cycle and according to the current different between channel currents.
The error amplifier has good noise rejection capability, but its transient response is poor to rapidly respond to the variation of the loading. Furthermore, the conventional multiphase converter circuit having the plural pulse width control circuit has the problems of complex circuit, larger die size and high cost, and further mismatch between the pulse width control circuits. The problems affect the definition of the channel current balance.